Re: [PATCH STABLE 4.9] x86, mm, gup: prevent get_page() race with munmap in paravirt guest

[Vlastimil Babka]

On 9/19/19 8:26 PM, Ben Hutchings wrote:
> On Mon, 2019-08-19 at 18:58 +0100, Vlastimil Babka wrote:
> [...]
> > Hi, I'm sending this stable-only patch for consideration because it's probably
> > unrealistic to backport the 4.13 switch to generic GUP. I can look at 4.4 and
> > 3.16 if accepted. The RCU page table freeing could be also considered.
>
> I would be interested in backports for 3.16 and 4.4.
>
> > Note the patch also includes page refcount protection. I found out that
> > 8fde12ca79af ("mm: prevent get_user_pages() from overflowing page refcount")
> > backport to 4.9 missed the arch-specific gup implementations:
> > https://lore.kernel.org/lkml/6650323f-dbc9-f069-000b-f6b0f941a065@xxxxxxx/
> [...]
>
> I suppose that still needs to be addressed for 4.9, right?

Yeah, I'll take a look, thanks for reminding.

> Ben.